The clinical usefulness of the melanin-seeking radiopharmaceutical iodine-123 DMQ (4,3 dimethylamino-propylamine-7-iodoquinoline) is being determined. Specifically, we are looking at patients with malignant ocular (choroidal) and skin melanomas. New detection devices include: 1) a dual pinhole eye collimator for use with a gamma camera, 2) a two eye-probe counting system (this allows simultaneous counting of 2 eyes), and 3) an ultrasound guided gamma probe (on loan from the University of Michigan). Large melanomas (1000 mm3) have been imaged but we do not know the limitations of the systems mentioned above, since too few patients have been studied. Patients are also being similarly studied with gallium-67 citrate. Laboratory investigations into the role of melanoma-localizing agents pre- and post-irradiation continue. We are using the Greene malanoma in the rabbit and gallium-67 citrate before and after irradiation with iodine-125. Our immediate goal has been to find a non-invasive method of determining the presence of an intraocular (choroidal) melanoma and then to evaluate the effects of radiotherapy and/or hyperthermia with melanoma-seeking radiotherapy and/or hyperthermia with melanoma-seeking radiopharmaceuticals.